1. Field of the Invention
The present invention relates to a rewritable image display apparatus that displays an image by forming the image using ink droplets.
2. Description of the Related Art
Nowadays, various rewritable image display apparatuses are proposed, for displaying a still image by forming the image through ejection of ink droplets toward an image display surface. Such image display apparatuses are applicable to bulletin boards that are installed at station premises and display various kinds of information concerning trains such as train arrival and departure information and train delay information; electronic whiteboards that are used, for instance, at the time of conferences and preliminary meetings; advertising boards, signboards, and the like.
The rewritable image display apparatuses have such an advantage that it is possible to perform rewriting with ease and to provide information smoothly as compared with provision of information using paper. In addition, amounts of electric power consumed by the image display apparatuses are smaller than those consumed by CRTs, liquid crystal displays, and the like.
Examples of the rewritable image display apparatuses are disclosed in JP 2002-169484 A, JP 2001-350425 A, JP 2001-209335 A, and JP 2001-109406 A.
In JP 2002-169484 A, for instance, an image display apparatus is proposed which includes an input unit for inputting image data, an image processing unit for processing the inputted image data, a recording head that forms an image, an image display surface on which the image formed by the recording head is displayed, and an image erasing unit for erasing the displayed image. With this construction, a labor time for exchanging advertisements printed on paper can be avoided, and it becomes possible for a passenger in a train to view every advertisement without moving in the train.
Also, in JP 2001-350425 A, an image display apparatus is proposed which includes: an image forming member having an image forming surface; an ink jet image forming means for forming an image based on image data using oily pigment-based ink dispersed in a low-volatile oily solvent; and an image erasing means for erasing the formed image. With this construction, miniaturization, a reduction in power consumption, and the like are achieved.
Further, in JP 2001-209335 A, an ink jet display apparatus is proposed which includes a mechanism for ejecting ink from nozzles of an ink jet recording head and sending a printing medium on which display information has been recorded, with the printing medium being an endless resin sheet.
Also, in JP 2001-109406 A, an image display apparatus is proposed which includes a means for applying a treating liquid containing a cationic substance onto a display medium, an image writing means having an ink ejection means for ejecting the ink, and a means for erasing an image displayed on the display medium. With this construction, an image blurring phenomenon can be prevented at boundaries between images in different colors that occurs due to blurring of ink and mixture of dots.
In the apparatuses of JP 2002-169484 A, JP 2001-350425 A and JP 2001-209335 A, however, adjacent ink droplets impinged on different positions of the image display surface for displaying an image, the image forming surface or the resin sheet may often contact each other, thus causing image blurring.
On the other hand, the apparatus of JP 2001-109406 A is an image display apparatus in which impinged ink is not mixed with each other. However, since a treating liquid containing a cationic substance is applied to the display medium prior to image formation and an image is then written using the ink ejection means, the treating liquid is always necessary as well as ink, which makes the apparatus construction complicated.